/*

 * Licensed to the Apache Software Foundation (ASF) under one

 * or more contributor license agreements.  See the NOTICE file

 * distributed with this work for additional information

 * regarding copyright ownership.  The ASF licenses this file

 * to you under the Apache License, Version 2.0 (the

 * "License"); you may not use this file except in compliance

 * with the License.  You may obtain a copy of the License at

 *

 *     http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */

package com.bff.gaia.unified.sdk.testing;



import com.bff.gaia.unified.sdk.coders.Coder;

import com.bff.gaia.unified.sdk.transforms.windowing.*;

import com.bff.gaia.unified.vendor.guava.com.google.common.base.Supplier;

import com.bff.gaia.unified.vendor.guava.com.google.common.collect.Iterables;

import com.bff.gaia.unified.sdk.transforms.windowing.BoundedWindow;

import com.bff.gaia.unified.sdk.transforms.windowing.IncompatibleWindowException;

import com.bff.gaia.unified.sdk.transforms.windowing.NonMergingWindowFn;

import com.bff.gaia.unified.sdk.transforms.windowing.WindowFn;

import com.bff.gaia.unified.sdk.transforms.windowing.WindowMappingFn;

import org.joda.time.Duration;



import java.util.Collection;

import java.util.Collections;

import java.util.Objects;



import static com.bff.gaia.unified.vendor.guava.com.google.common.base.Preconditions.checkArgument;



/**

 * A {@link WindowFn} that assigns all elements to a static collection of {@link BoundedWindow

 * BoundedWindows}. Side inputs windowed into static windows only support main input windows in the

 * provided collection of windows.

 */

final class StaticWindows extends NonMergingWindowFn<Object, BoundedWindow> {

  private final Supplier<Collection<BoundedWindow>> windows;

  private final Coder<BoundedWindow> coder;



  private final boolean onlyExisting;



  private StaticWindows(

      Supplier<Collection<BoundedWindow>> windows,

      Coder<BoundedWindow> coder,

      boolean onlyExisting) {

    this.windows = windows;

    this.coder = coder;

    this.onlyExisting = onlyExisting;

  }



  public static <W extends BoundedWindow> StaticWindows of(Coder<W> coder, Iterable<W> windows) {

    checkArgument(!Iterables.isEmpty(windows), "Input windows to StaticWindows may not be empty");

    @SuppressWarnings("unchecked")

	StaticWindows windowFn =

        new StaticWindows(

            WindowSupplier.of((Coder<BoundedWindow>) coder, (Iterable<BoundedWindow>) windows),

            (Coder<BoundedWindow>) coder,

            false);

    return windowFn;

  }



  public static <W extends BoundedWindow> StaticWindows of(Coder<W> coder, W window) {

    return of(coder, Collections.singleton(window));

  }



  public StaticWindows intoOnlyExisting() {

    return new StaticWindows(windows, coder, true);

  }



  public Collection<BoundedWindow> getWindows() {

    return windows.get();

  }



  @Override

  public Collection<BoundedWindow> assignWindows(AssignContext c) throws Exception {

    if (onlyExisting) {

      checkArgument(

          windows.get().contains(c.window()),

          "Tried to assign windows to an element that is not already windowed into a provided "

              + "window when onlyExisting is set to true");

      return Collections.singleton(c.window());

    } else {

      return getWindows();

    }

  }



  @Override

  public boolean isCompatible(WindowFn<?, ?> other) {

    if (!(other instanceof StaticWindows)) {

      return false;

    }

    StaticWindows that = (StaticWindows) other;

    return Objects.equals(this.windows.get(), that.windows.get());

  }



  @Override

  public void verifyCompatibility(WindowFn<?, ?> other) throws IncompatibleWindowException {

    if (!this.isCompatible(other)) {

      throw new IncompatibleWindowException(

          other,

          String.format(

              "Only %s objects with the same window supplier are compatible.",

              StaticWindows.class.getSimpleName()));

    }

  }



  @Override

  public Coder<BoundedWindow> windowCoder() {

    return coder;

  }



  @Override

  public WindowMappingFn<BoundedWindow> getDefaultWindowMappingFn() {

    return new WindowMappingFn<BoundedWindow>(Duration.millis(Long.MAX_VALUE)) {

      @Override

      public BoundedWindow getSideInputWindow(BoundedWindow mainWindow) {

        checkArgument(

            windows.get().contains(mainWindow),

            "%s only supports side input windows for main input windows that it contains",

            StaticWindows.class.getSimpleName());

        return mainWindow;

      }

    };

  }



  @Override

  public boolean assignsToOneWindow() {

    return true;

  }

}